Synthesis and property characterization of precursor-derived ceramics reinforced by functionalized single-wall carbon nanotubes

本项目旨在合成和研究新型前驱体衍生陶瓷基复合材料，其中单壁碳纳米管(SWCNTs)作为极限机械强度和回弹的增强材料。其核心目标是赋予以SiCN或SiBCN为陶瓷基的复合材料具有高的力学、电学和热性能。为此，必须对高纯度的单壁碳纳米管进行化学功能化，以获得分离良好的管，并控制陶瓷和纳米管之间的界面结合，以确保有效的管分散和负载转移。设计的化学官能化包括单壁碳纳米管的氟化和硅基化，这应该能够通过不同的策略使纳米管共价锚定在前体分子上。为了在微纳米尺度上研究复合材料的力学性能和断裂机理，基于热载荷方法的测量将被双轴弯曲测试和纳米压痕测试所补充，特别是研究硬度、杨氏模量和断裂韧性随合成和加工条件以及纳米管含量和官能化程度的变化。特别是，含有未改性单壁碳纳米管的复合材料和含有功能化管的复合材料之间的比较将揭示所设想的界面耦合导致材料性能增强的程度。沿着同样的路线，我们将研究纳米管增强复合材料的导电性和导热性。最后，应进行详细的微观研究，目的是将单壁碳纳米管/陶瓷纳米复合材料−的主要结构特征，如纳米管−的结构完整性和分布与其机械、电学和热学性能相关联，从而帮助确定这些材料的最佳制造参数和组成。

This project aims at the synthesis and investigation of novel precursor-derived ceramic matrix composites with single-wall carbon nanotubes (SWCNTs) as reinforcement of ultimate mechanical strength and resilience. The central goal is to confer high mechanical, electrical and thermal performance to composites composed of SiCN or SiBCN as ceramic matrix. To this end, high purity SWCNTs shall be chemically functionalized in order to obtain wellseparated tubes as well as to control the interfacial bonding between the ceramic and the nanotubes to ensure efficient tube dispersion and load transfer. The devised chemical functionalization encompasses the fluorination, as well as the silylation of SWCNTs, which should enable covalent anchoring of the nanotubes on the precursor molecules through diverse strategies. For investigating the mechanical properties and fracture mechanism of the composites at the micro/nanoscale, measurements based upon a thermal load method will be complemented by biaxial flexure tests, nanoindentation testing, specifically addressing hardness, Young's modulus and fracture toughness as a function of the synthesis and processing conditions, as well as the nanotube content and functionalization degree. In particular, the comparison between the composites comprising unmodified SWCNTs and those containing functionalised tubes shall reveal the extent to which the envisioned interfacial coupling leads to enhanced material performance. Along the same line, the electrical and thermal conductivity of the nanotube-reinforced composites will be studied. Finally, detailed microscopic investigations shall be performed with the aim of correlating major structural features of the SWCNT/ceramic nanocomposites − such as the structural integrity and distribution of the nanotubes − with their mechanical, electrical and thermal properties, thus aiding to identify the optimal fabrication parameters and composition of these materials.